Changes in version 0.1.0 (2026-05-05)                  

New functions

  - gsrs_search(): free-text and Lucene-syntax search across GSRS
    substances, with optional automatic pagination.
  - gsrs_substance(): fetch substance metadata by UNII (vectorized).
  - gsrs_names(): retrieve all registered names / synonyms for one or
    more UNIIs.
  - gsrs_codes(): retrieve all cross-reference codes (CAS, PubChem,
    ChEMBL, WHO-ATC, DrugBank, etc.) for one or more UNIIs, with
    optional code_system filter.
  - gsrs_unii_from_name(): resolve substance names to their UNII
    identifiers.
  - gsrs_structure(): fetch chemical structure data (SMILES, formula,
    MW, InChI, stereo info) by UNII.
  - gsrs_structure_search(): substructure, similarity, exact, and
    flexible structure search by SMILES.
  - gsrs_chem_info(): retrieve chemical structure information from any
    identifier — name, CAS, UNII, InChIKey, or SMILES.
  - gsrs_hierarchy(): retrieve the parent/child relationship tree for a
    substance.
  - gsrs_browse(): page through the full GSRS substance catalogue.
  - gsrs_vocabularies(): retrieve all controlled vocabulary terms.
  - gsrs_all(): convenience umbrella returning substance metadata,
    names, codes, structure, and hierarchy in a single named list.
  - write_dataframes_to_excel(): write a named list of data frames to an
    Excel workbook (requires openxlsx).